Modelling The Transport and Return of Chloride Using INCA-Cl in an Urbanizing Watershed

1.0 Introduction In northern environments such as Canada, road salt (e.g. sodium chloride, NaCl) has been used as a de-icing agent to improve winter driving conditions since the 1950’s (Godwin et al., 2003). While research has shown that the application of salt to roadways can reduce accident rates by up to 88%, the use of road salt has been linked to increasing concentrations of chloride (Cl) in ground and surface waters in urbanized watersheds (Godwin et al., 2003). A recent study (Dugan et al., 2017) which tested 371 lakes in north eastern North America found that 44% trended towards long term salinization – levels at which Cl concentrations may begin to impact freshwater ecosystems. High Cl concentrations have been found to be potentially lethal to aquatic organisms, and long-term exposure can have detrimental effects on human health (Howard and Beck, 1993; Kelly et al., 2008). Keeping lakes and rivers “fresh” is important for the maintenance of ecosystem services associated with freshwater resources such as drinking water, fisheries and aquatic habitat.